Well sounding apparatus



Nov. 19, 1946. A. woLF rA| WELL SOUNDING APPARATUS Filed Aug. 22, 1944 wine-e K ATTORNEY Patented Nov. 19, 1946 WELL soUNDING APPARATUS Alexander Wolf and Laurence G. Cowles, Houston,

Tex., assignors to The Texas Company, New I York, N. Y., a corporation of Delaware Application August 22, 1944, Serial No. 550,662

This invention relates to a method and apparatus for measuring the location or depth below the ground surface of the liquid level in a deep well, whether the liquid therein be oil, water or a mixture of water and mud. More specifically, the invention relates to an apparatus for receiving and recording pressure vibrations or impulses which result from the direction of a pressure wave into a well and which are reflected from the surface of the liquid in the well as well as from tubing collars and other obstructions.

Acoustical methods of determining the depth of the level in deep wells have been utilized before and as typical of these prior methods, reference is made to those employing sound waves and to those employing pressure waves produced by introducing a shot of relatively high intensity into a well to produce pressure waves therein.

@According to the former method, the elapsed time between the introduction of the sound and its return as an echo from the surface of the liquid is noted and recorded. In a similar manner, the latter method measures the elapsed time y 'between the introduction of the shot into the well and the return of the pressure waves produced' thereby.

More specifically, the present invention relates to an apparatus which is particularly sensitive to fluid reflections obtained in some deep wells such as those produced by a sharp explosion resulting from the firing of a blank cartridge in a suitable firing device. The pressure wave thus produced travels the length of the well casing, portions being reected back from the tubing collars or casing joints, and the remainder being reflected back lfrom the surface of the liquid in the well. In

some cases, it is not practical or desirable to place the receiver or microphone in which the reected pressure impulses are picked up and recorded in a position where they are in communication with the well casing because of the possibility of damage to the microphones by reason of the static pressure in the casing and also because the corrosive action of the well gases tends to damage the microphone.

One of the yobjects of the present invention is to provide a well sounding device including a microphone or other pickup device for receiving pressure impulses as reected from the surface of liquid in a well and in which the microphone is not directly exposed to the gases or static pressure in the well.

Another object of the invention'is kto provide in such a device a pressure responsive element which is operatively connected to both the well casing and the microphone for transmitting the pressure impulses from the inside of the casing to the microphone while preventing direct contact of the well gases with the microphone. In order to carry out the above-mentioned objects,

3 Claims. (C1. 177-352) the invention contemplates the use of a pressure responsive curved tubular element such as a Bourdon tube or gauge which is arranged with its open end in direct communication with the well casing whileits opposite end is closed and oper-x atively connected to the diaphragm of the microphone. Any movement of the closed end of the Bourdontube in response to fluctuations of pressurein the well casing actuates the mech- 4anism connecting the tube with the microphone diaphragm and corresponding actuation of the latter is effected. The vibrations of the diaphragm are then recorded ina well-known manner.

Figure .1 is a, diagrammatic view showing in cross section a conventional type of well assembly, together with the apparatus for determining the liquid level inthe well, a portion of the impulse receiving device `being shown in cross section;

Figure 2 is an venlarged `view `of the impulse receiving device;

Figurer 3 Vis a schematic view of a modied form of the present invention;

1 Figurev 4 is a diagram showing electrical connections including a balancing arrangement consisting of two variable condensers, and

Figure 5 is a diagram of another arrangement of electrical connections includinga balancing arrangement consisting of a slide wire potentiometer.

In Figure 1 there is illustrated a, conventional type of oil well having a relatively large casing l0 composed of a plurality of sections which extend from above the ground level l2 downwardly into the well. The several sections comprising the casing arefsecured `together in any desired manner. A second pipe or tubing 'string I4 which also is. composed of a plurality of sections secured together by means of collars I6 extends downwardly to a point below the level of fluid in the well and at its lower end the pipe I4 carries a pump of any desired character (not shown).

. The pump ordinarily is operated by means of a Y 26 is connected, the open end of the tube being arranged in open communication with the branch pipe 24. When the Bourdon tube 26 is subjected to internal pressure it tends to straighten out,

vthus causing deflection of its closed end, the degree and frequency of deflection being proportional to the amount of pressure exerted within.

The firing device 28 which produces the pressure wave in the well is attached to the free end of pipe 22.

The fluctuations in pressure impulses as reiected by the movement of the end of the Bourdon tube 26 are imparted directly to a crystal pickup device 30 which preferably is a standard piezoelectric phonograph pickup but may very well be a microphone of any suitable type. An angle iron 32 is attached to the end of the Bourdon tube, the free end of the angle iron being provided with a hole to accommodate a screw 34 by means of which a longitudinally adjustable slotted link 36 is attached to the angle iron. A stiff wire or needle 38 is placed in the'phonograph pickup 30 and the free end of the wire is soldered to the link 36. With this construction any' movement of the end of the Bourdon tube 26 is imparted through the wire 38 to the pickup device 30. In practice the well pressure is rst applied to the Bourdon tube and after the tube has moved into a position determined by the static casing pressure, the screw 34 in the link 36 is tightened in order that the pickup device 30 will respond to changes in average casing pressure without being subjected .to the static pressure.

The pickup device 30 is connected to a recording device 4D, preferably through an amplifier 42, where the energization created in the pickup device is recorded in a well-known manner. assembly including the Bourdon tubel 26 and pickup device 30 may', if desired, be enclosed in a metal box or housing 44 to protect the assembly from the weather and to shield the crystal in the pickup device from external electrical interference.

A pickup arrangement of the type described is sometimes too sensitive to external mechanical vibrations and in order to overcome this condition two Bourdon tubes attached to a common intake can be employed. As shown in Figure 3, two oppositely disposed Bourdon tubesV 2,6 and 26" are arranged with their open ends in communication with the free end of pipe 24. The two tubes are connected'in the manner described above to separate crystal pickups 30' and 30", respectively. The outputs of the two pickups are connected to a recording device 40 either in parallel, or in series as shown in Figure 4. An amplifier 42 may if desired be interposed between the output of the pickup devices and the input of the recording device and in some instances it is desirable to introduce a kbalancing arrangement such as two variable condensers 46 as indicated in Figure 4 or in the alternative, a slide wire potentiometer 48 as shown in Figure 5 may be Y connected across the output of the pickup devices.

From the foregoing it is apparent that variations in pressure within the well casing will result in identical voltages of the same polarity from the two pickups 30' and 30" which voltages will then be recorded in the recording device 40. On the other hand, because of the relative disposition of the two Bourdon tubes 26 and 26", external mechanical vibration of the entire system will result in identical voltages of opposite polarity from the two pickups because whenever the end of the tube 26' is caused to move to the right relative to the pickup device 30 with which it is connected, the end of the tube 26" will be caused to moveto the left relative to the pickup device 30" with which it is connected. The two voltages of opposite polarity when added together The 4 will be nullied but if, because of different sensitivities of the two pickup devices these voltages do not cancel each other, a. complete cancellation may be effected by using `the balancing condensers 46 as shown' in Figure 4 or a balancing potentiometer 48 as hereinbefore described.

From the foregoing it will be seen that when a shotgun blank is exploded in the gun cartridge chamber of the ring device 28 the pressure wave created by the explosion traverses the length of the pipe 22 and passes into the well casing I0. The impulses reflected by obstructions such as the collars I6 on the tubing string I4, together with the'impulses reflected from the surface of the liquid in the well return through the casing I0, pipe 22 and through the branch pipe 24 tothe Bourdon tube 26. Upon entering the tube, the pressure waves act upon the curved portion 0f the tube and tend to straighten it and this movement of the end of the tube 26 is transmitted to the pickup device through the connecting wire or needle 38 and acts upon the crystal of the pickup device to produce energization of varying degrees, which energization is then transmitted to a. recording device either directly or through an amplifier.

Theoperation of the arrangement shown in Figure 3 is substantially the same except that voltages are produced in the two pickup devices 30 and 30, the outputs of which are connected either in series or in parallel to the recording device 40. As stated hereinbefore, if necessary f variable condensers 46, 46 or a slide wire potentiometer 48 may be interposed between the outputs of the pickup devices and the amplifier in order to balance the voltages of the pickup devices.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. The combination with a well casing, of means for receiving and recording pressure irnpulses from the well comprising a plurality of Bourdon tubes mounted upon a common support with their open ends in communication with the well and oppositely disposed upon said support to reduce vibrationally induced voltages, means connecting the closed ends of each of said Bourdon tubes with a pressure-sensitive pickup device to actuate said device in response to changes in the curvature of said tubes resulting from changes in pressure therein, means for balancing the amplitudes of the voltages emanating from said pickup devices to overcome differences in the sensitivity of said devices, and a recording device operatively connected to said balancing means for recording impulses transmitted to it from said well by said pickup devices.

2. An apparatus according to claim 1 in which said balancing means comprises a slide wire potentiometer connected across the outputs of said pickup devices.

3. An apparatus according to claim 1 in which said balancing means comprises a variable condenser connected across each of said pickup deces.

ALEXANDER WOLF. LAURENCE G. COWLES. 

